<?php
$grades = array(1,2,3,4,5,6,7,8,9,10,11,12);
?>
<form>
  <select name="grades">
		<?php foreach($grades as $value) : ?>
			<option value="<?php echo $value; ?>">第<?php echo $value; ?>周</option>
		<?php endforeach ; ?>
	</select>  
</form>

